Leaching copper and like ores



Patented ll ecl l2, i

inte se v. i o in 1 t 7' a w t i In; l i i ll 1 limit HENRY B. strewn/onnrvnnsnon, cetrronnm.

LEAGHING COITEE AND LIKE i No Drawing.

10 ing of ores torthe purpose of producing a,

solution. containing the metal values of the ores, and is particularlyapplicable to the extraction of copper from its ores for the su'lo-lsequent recovery from the said solution of the metal values by anysuitable process.

'Sulfide ores of copper in order to be amenable to leaching by sulfuricucid, have to be subjected first to an oxidizing roast or e chloridizingroas; in order to convert the O are readily attached by dilutesulturicacid. Accordingly, in the leaching of copper from sulfide ores, it hasbeen the usual custom to subject the sulfide oresto suitable roastingoperation, which may be u sultetizing roast, a deed roast or achloridizing roast and with certain cle dii'licult .touget complete convsulfides by this operation; when such ores are roasted, and then leachedwith sulfuric acid, any sulfides remaining in the roasted product willnotordincrily be leached by the acid. while, of course, it would bepossible to dry the lcuchcd residue and then subject the some to a,second roasting operution this would notbe ordinarily feasible in.commercial practice on account of the great amount of heart which wouldbe required to drive of? all ot' the w nter -from the leached tailing-s.v i i n In order to complete the extraction of such oxidized orecontaining an illlOXlCllZfitl (sulfide) portion, l preferably" cecd asfollows: The ore, which may be l not absolutely completely) 021i 4jected (to the action of dilute sulfuric in excess, this acid dissolvingall the cop- "per which exists in the form of sulfate and alerge part ofthe copper whicheizists in in of the bulk of the acid leach solution isthen drawn oil from the ore and to the ore, contaln copper compoundsinto compounds which t sses of ore, it svextreinely (but the form ofoxide, but doesnot dissolve the copper which in the form. oi? sulhd. The

chlorite, these if desired, but is ordinarily not necessary.

mmifi d e iileieei. Serial No. ease/35.

sodium hypochlorite or; calcium hyporeagents preferably being in theform erelecively concentrated solution. hfloresulturic acid may be addedThe mixture of ore materiel and acid leech solution remaining andlljyPOChlOlltQ$0111- tion are preferably agitated more or less until thereaction is complete or substantially complete. The sulfuric acid,remaining in the ore readily reacts with the hypochlorite to formsulfate and hypochlorous .ecid, which letter reedily reects with thesulfide of copper in the ore, giving a substantially complete extraction01 the copper.

llhe first acid leech solution utter being Withdrawn from contact withthe ore, mey

in this leech liquor; The leuchliquor from the hypochlorite treatmentmay like L i ccordingly,

treatment with ore, and used wise be brought into contact with anotherbutch oi. orev materiel touutilize its content of free acid,

The acid leaching solution containing sulfuric ccid and t 1c second ecidleaching solution may be brought "to 'ethen after on a, further quantityof ore. The finsl pregnentrsolution will bepuriiied in any suitablemanner; and can thenbe run into enelectrolytic vet, for theprecipitation of the copper therefrom,

with the regeneru'ticncf sul'i uricncid' suitable for use in leu hing;additional quantities i of ore,

In the above description I have referred to the treutmenc of sulphideores containing v a substun ing, some free acid and water is thencopper, by roos ing; in appropriate manner. then leaching" with.sulfuric acid and then while the ore still contains sulfuric acid,treating with e hypochlorite to attack the copper aininc; in the orefrom the sulfuric acid treatment, The process is also applicable to oresvhich contuin copper in any form in which clll proportion of e copperisnot readily ieuiheble bysulfuricncid, an ex- :unplcci" such othercresould be 01365100111, tuininp; p i ry or nl ive copper ores. The processis 'lewise applicable to the treatment of concern those produced inflotation processes. 'Whilethe process has been referredftoin conn ctionwith the treatment of sulfid' ores 1 including copper; itisels'o'epplicable to the.

cs or toillings, such treatment of ores containing other metal sulfidores, such as those oi Z nc, lead, or silver, or mixed ores containingcopper and one or more of these,.withx r FVliIllOllll gold.'

completely ex- For purpose of 1110' .naon the folplainingthe nature ofthe lowing; examplesqare given, it being unnei stood that the inventionis not restricted to these examples: I 7 Michiganorc toZiw/ /s. I

The ones ofthefMichigan district all carry their copperhsnative ormetallic cop' per but thetailings from the concentration tables, as Wellthe sands so-callechthat are now being recovered from the lakes,

where theyhave been discarded for years, all carry some oxidizedmineral, and

because of this, the attempts at recovery by flotationhave not been verysuccessful. in addition to the oxidized copper, also there is more orless limein these tailings and sands @Analysisj Cu 'sioi Fegoi A1263C-aO MgO Total o.ee%-41;79% 12.43% 23.04 16 .90% 3.97% 99.26%

Of the copper" content 26.5 issoluble in H 50, and of the remainingcopper 91.4%

v The flotation tails is representative of the.

p i equals 15.70 lbs. per ton.

table tails.

issoluble in the hypochlorite solution after I the acid solution isdrawn on. The total extraction equals 96.68%. p Second Michigan arematerial.

wThis is designated under the names flotation heads and flotation tails.

Theflotation heads is representative of the table tails from theconcentration mill.

sailings, from the flotationjprocess adopted for the recovery of thecopper from the ".Flotation heads carried Cu:O.785%

Flotation heads carried CitUzEZJfZZ. Flotation tails carried Cu:().33%equals v 6.6 lbs. per ton.

* going to aste.

" Flotation tails carried 0:19:27 5%.

By flotation less than o'l 'the copper in the ore is recovered. Over43%; of it is My experiments repeatedly prove t practical extraction ofmore than 0 of tile i j copper content of the flotation heads or beterthan 14 lbs. per ton, This is better than could be recovered byfiotation.

Arizona ore.

This ore represents a tairsa'inple of the .porphyries of the Southwest,upon which I much effort is being expended for the applicationfoftheflotation process; Flotation beingapplicable to the extraction of thesulphides but not so the carbonates, silicates and oxides. F or thesecompounds of copsolution. Thismeans a second'stage in theflotationoperation With the necessary m chanioal'handling in each stage.v

This ore carries copper as sulphides and oxidized compounds. Apparentlysome culprite and some chalcopyrite, but inostlyas chalcocite, azurite,malachite and chrysocolla. V

Sulphuric acid has but very little action upon the sulphides but actsfreely upon the carbonates, silicates and oxides.

Hypochlorous acid has .but little, if any,

action onthe oxides, carbonates or silicates, but. acts powerfully andrapidly on the sulphides. The products of oxidation of a sulphideby'hypochlorous acid are hydrochloric and sulphuric acids and these actvigor ously upon thecarbonates, silicates and oxides of copper.

Act/ion of hypcchlorous acid on chalcocite.

I CruS plus lHClO equals 2CuCl plus H 550 plus QHCI.

C11 8 plus SHClO equals QCuCl plus Upon pure mineral the eiiiciencywould be 2C1 for each Cu, but on a mixed ore,

containing; oxides, carbonates, and silicates as well as chalcocite, thesulphuric and bydrochloricacids act as leaching agents and then theefficiency of the reaction Will be lCl for each 601i.

Second Arizona 01:6,00assting of sandsand climes. v

The sands in this case is the ore crushed to pass 80 mesh screen, fortable concen tration, and the sliinesis irreducible Inaterial, ofiinpalpable fineness, from which nothing; furtherotl? value can beextracted bythe ordinary methods concentration.

Analysis of sands.

' Lesson SiO2 F020 A1 03 CaO MgO ignition Cu Sv 3.65% 051% 63.64% 353%16.77% Trace 0.53% 10.98%

Of the copper content is soluble in li fifi and of the remaining copperrecoverable by use of the hypo= chlorite solution, added to the pulpafter draining oil the 'majorpart of the sulphuric acid solution. Thetotal extraction is.94i.5%.

Analysis of slimes,

. I Loss on Cu 8 s10 F9203 A1203 CaO Mgo ignition 1.66% 0.49% 57.91%2.60%"22.2s% .Trace 1.76% 13.26%

Of the copper content 33.73% is soluble in 5% n so nd of the remainingcopper messes 90% is soluble in the hypochlorite solution, added to thepulp after draining 0a"- the sulphuric acid solution. The totalextraction from the slimes by my process being 93.3% of the coppercontent.

Chilean copper me.

is soluble in the hypochlorite solution after draining oil? the acidsolution, Total traction equals 94%.

Mixed ores, concentrates, or tailing s.

The process is accordingly adapted for the treatment of mixed sulphideand oxidized ores of copper withoutthe need of a preparatory calciningor roasting.

The process consists of, or embodies, the following steps:

Firsti Reduction, by grinding, to a suitable fineness.

Second: Leaching with sulphuric acid for the extraction of the oxidizedportion of the copper, leaving in the pulp suflicient of the acid forthe reactions of the next step.

Third: Leaching with a solution of a hypochlorite oi sodiumor calcium,which solution, being acted upon by the residuary acid of the previousstep, is productive of hypochlorous acid which in oxidizing thesulphides of copper in the ore is productive oi? sulphuric acid andhydrochloric acid and they dissolve the oxides oi copper thus formed.

The solution used in the third step (in the various modifications given)should preferably also contain a suflicientamount of con1- mon salt tohold in solution all of the cuprous chloride formed inthe reaction,

Hypochlorite solutions as ordinarily produced may in some cases containa suifi: cient amount of common salt for the purpose, for example asolution of sodium hypochlorite made from bleaching powder ordinarilywill contain rather more of sodium chloride than of sodium hypochlorite.It is to be'understood that any deficiencies of sodium chloride caneasilybe made up by adding common salt to the hypochlorite solution usedor to the ore pulp remaining after a. considerable amount of thesulfuric acid leaching solution has been drawn ofi.

In connection with theleaching of roasted ores, l v dilute sulphuricacid in excess it may be noted that in ordinary ore roast ing operationsin which sullid ores are treated, the roastingis carried to a point atwhich the major part of the sulphur is OX- idized sometimes to sulfateand sometimes to sulfur dioxid, and sometimes partly to sulfate andpartly to sulfur dioxid. These roasted ores, even when considered by themetallurgist as being completely roasted, usually carry a small amountof sulfur in the form of sulfid, which cannot be oxidized without exce.sive loss of time and excessive waste of fuel.

I claim: p

1.. A. process of leaching metal values .t'rom material containing suchvalues existing therein n part at least, as sulfid, which M, l comprisesreacting upon such material with an acid leaching solution in excess,and thereafter reacting thereupon with a chlorin-onygen compound in thepresence or free acid.

2. A process of leaching metal values, from material containing suchvalues existing therein, in part at least, as solid, which comprisesreacting upon such material with an acid leaching solution in excess,and thereafter reacting thereupon with an oxidim ing reagent in thepresence of an acid, such mixture being capabl of liberating achloridizing reagent.

3. A process of leaching metal values trom material containing suchvalues existing therein, in part at least, as sulfid, which comprisesreacting upon such material with an acid leachi. solution in excess, andthereai u reacting thereupon with a hypochl its material in the presenceof an acid which is capable oi displacing hypochlorous acid from itssalts.

i. A. process of leaching metal values from copper-bearing materialcontaining some sulfide, which con'iprises reacting upon such materialfirst with a sulfuric acid leaching solution, the acid; being in excess,and there after reacting upon the r sidue with a hypochlorit-e in thepres nceo; tree sulfuric acid.

5. A process of leaching copper values from copper bearing materialcontaining a portion of its copper content in a form in which it is notreadily soluble in dilute sulfuric acid which comprises first leachingthe said material with sulfuric acid leaching solution, the acid. beingin excess and there a after reacting upon a residue with hypo-- chlorousacid compound.

In testimony wherof I aflii; my signature- HENRY B. SLATER.

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